Here are some thoughts I have regarding how I wrote The Diamond Series vs how I am writing a new story, which is a Teen Titans / Devil May Cry Crossover.
Choosing a Rating for The Diamond Series
With the Sonic stories, I shifted to the tone up to 15+ so I could do some more adult things without getting explicit. It wasn't until I reached Watch Dogs of the ARK that I took that up a notch and featured a few arguably 18+ things, such as suggestive dialogue, mild foreplay, and slightly more detailed violence. To me, this pushed the story up to a tame Mature status. Still, I tried to maintain, in all of the Diamond stories, a somewhat accurate tone to the worlds of Sonic. However, I am not attempting to be 100% tonally true to the Teen Titans world, since I have inserted this M-Rated character.
The One Crossover Currently Posted
So I think crossovers are tricky. I have one posted currently, A Questionably Long Darkwing Story. I messed around with that story on and off for about a decade before posting it. It was originally 2 stories but I mashed them into one. It's a mild crossover featuring a Shadow Android and a brief appearance from Rouge the Bat (her reason for being there is actually referred to in Shadowless World). This story takes place in the 90's Darkwing Universe and doesn't go much into the world of Sonic. I even made it so that the Damn Fourth Chaos Emerald can talk in this story, implying that it has different powers when placed in the land of Darkwing Duck.
DMC5 Meets DC
There's a lot I can do with the Teen Titans universe that I can't do in the realms of anthropomorphic characters such as, Sonic or Darkwing Duck. I'm not interested in showing gore or excessive profanity in Sonic or Darkwing stories, as that does nothing to serve the original vibe of those series'. If I was only writing within the Teen Titans Animated Series world I would likely keep the rating at 15+ and spare the reader from violence and the morbidity. Though I would touch further on the human aspects on the characters. However, the world of DC does not shy away from dark themes (Harley Quinn, the Joker, Batman, etc.) and the world of Devil May Cry welcomes them. So if you are into DC in general, the tone of my new story will probably not be too unfamiliar. Another point to mention is that there are games which place Capcom Characters with Marvel Characters, if you're interested in watching Deadpool and Dante beat the crap out of each other.
Summarized Disclaimer
The new story has themes surrounding death and loss and contains no shipping whatsoever. 18+ though as I stated in the description of Watch Dogs of the ARK, your level of maturity is your call. The Mature tag will be there so if you find things are getting to be too much, please move on to another story.
